Chevelle Fuel Gauge Problem

**Damien** · #1 10-20-2014, 01:09 AM

Hi guys.
The fuel gauge in my '70 SS has never worked correctly since owning the car. Has never read past half and at one stage didn't work at all. All the gauges were replaced by the previous owner with repro stuff. I have tested the sender in the tank and all seeems ok so it looks like a ground or a gauge issue. I have found 3 grounds under the dash, one on the e brake bracket and two under the dash, mounted together onto bare metal. Should there be one or two more grounds under the dash that I haven't found? If the grounds all check out it, have I confined it to a gauge or electrical dash issue? Is there something obvious I have overlooked? Just trying to eliminate everything before I take on the job of pulling the dash either part way or completely out of the car. Any suggestions appreciated. Thanks in advance.

**DaveC68** · #2 10-20-2014, 01:23 AM

May be of some help...

http://www.firstgenmc.com/forums/ind...Bunit+%2Bfloat

http://www.chevelles.com/forums/show....php?p=3025260

**Zman1969** · #3 10-22-2014, 05:39 PM

may look here - made diagnosing my sender easy!
http://www.camaros.net/forums/showthread.php?t=195833

**Damien** · #4 10-22-2014, 07:46 PM

Zman, thanks for that. I have eliminated everything from the fisher connector under the dash back to the sender. So it looks like an electrical problem under the dash, whether it is a bad ground, some messed up wiring, a bad gauge or the pcb is no good or not grounded properly? I have searched a lot of stuff on TC and will get back into the search on the weekend. Gotta love electrical issues, huh! [img]<<GRAEMLIN_URL>>/thumbsdown.gif[/img]

68z28kk · #5 10-22-2014, 09:22 PM

The tank unit is the only ground to the gas gauge. With the key on and the tan wire in the trunk connector unplugged to the gauge. The gauge should read beyond full. If it doesn't move you need to test for 12 volts at the + side of the guage. If 12 volts is present and it doesn't go to full it's either the dash gauge or the resistor that is on the back of the gauge. All the other grounds under the dash don't affect the gas gauge operation. Once the dash gauge works as described above the tank unit is a resisted ground and is simple to test.

**Damien** · #6 10-22-2014, 10:38 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 68z28kk</div><div class="ubbcode-body">The tank unit is the only ground to the gas gauge. With the key on and the tan wire in the trunk connector unplugged to the gauge. The gauge should read beyond full. If it doesn't move you need to test for 12 volts at the + side of the guage. If 12 volts is present and it doesn't go to full it's either the dash gauge or the resistor that is on the back of the gauge. All the other grounds under the dash don't affect the gas gauge operation. Once the dash gauge works as described above the tank unit is a resisted ground and is simple to test. </div></div>

Thanks for that. I've done the sender test and it came up ok, but didn't know the other gauge info you posted above so i will check that out.
Thanks again.